Index: cfe/trunk/include/clang/Basic/BuiltinsX86.def
===================================================================
--- cfe/trunk/include/clang/Basic/BuiltinsX86.def
+++ cfe/trunk/include/clang/Basic/BuiltinsX86.def
@@ -641,6 +641,9 @@
 //CLFLUSHOPT
 TARGET_BUILTIN(__builtin_ia32_clflushopt, "vvC*", "", "clflushopt")
 
+//CLWB
+TARGET_BUILTIN(__builtin_ia32_clwb, "vvC*", "", "clwb")
+
 // ADX
 TARGET_BUILTIN(__builtin_ia32_addcarryx_u32, "UcUcUiUiUi*", "", "adx")
 TARGET_BUILTIN(__builtin_ia32_addcarry_u32, "UcUcUiUiUi*", "", "")
Index: cfe/trunk/lib/Headers/CMakeLists.txt
===================================================================
--- cfe/trunk/lib/Headers/CMakeLists.txt
+++ cfe/trunk/lib/Headers/CMakeLists.txt
@@ -33,6 +33,7 @@
   clzerointrin.h
   cpuid.h
   clflushoptintrin.h
+  clwbintrin.h
   emmintrin.h
   f16cintrin.h
   float.h
Index: cfe/trunk/lib/Headers/clwbintrin.h
===================================================================
--- cfe/trunk/lib/Headers/clwbintrin.h
+++ cfe/trunk/lib/Headers/clwbintrin.h
@@ -0,0 +1,52 @@
+/*===---- clwbintrin.h - CLWB intrinsic ------------------------------------===
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ *===-----------------------------------------------------------------------===
+ */
+
+#ifndef __IMMINTRIN_H
+#error "Never use <clwbintrin.h> directly; include <immintrin.h> instead."
+#endif
+
+#ifndef __CLWBINTRIN_H
+#define __CLWBINTRIN_H
+
+/* Define the default attributes for the functions in this file. */
+#define __DEFAULT_FN_ATTRS __attribute__((__always_inline__, __nodebug__,  __target__("clwb")))
+
+/// \brief Writes back to memory the cache line (if modified) that contains the
+/// linear address specified in \a __p from any level of the cache hierarchy in
+/// the cache coherence domain
+///
+/// \headerfile <immintrin.h>
+///
+/// This intrinsic corresponds to the <c> CLWB </c> instruction.
+///
+/// \param __p
+///    A pointer to the memory location used to identify the cache line to be
+///    written back.
+static __inline__ void __DEFAULT_FN_ATTRS
+_mm_clwb(void const *__p) {
+  __builtin_ia32_clwb(__p);
+}
+
+#undef __DEFAULT_FN_ATTRS
+
+#endif
Index: cfe/trunk/lib/Headers/immintrin.h
===================================================================
--- cfe/trunk/lib/Headers/immintrin.h
+++ cfe/trunk/lib/Headers/immintrin.h
@@ -58,6 +58,10 @@
 #include <clflushoptintrin.h>
 #endif
 
+#if !defined(_MSC_VER) || __has_feature(modules) || defined(__CLWB__)
+#include <clwbintrin.h>
+#endif
+
 #if !defined(_MSC_VER) || __has_feature(modules) || defined(__AVX__)
 #include <avxintrin.h>
 #endif
Index: cfe/trunk/test/CodeGen/builtin-clwb.c
===================================================================
--- cfe/trunk/test/CodeGen/builtin-clwb.c
+++ cfe/trunk/test/CodeGen/builtin-clwb.c
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 %s -ffreestanding -triple=x86_64-apple-darwin -target-feature +clwb  -emit-llvm -o - -Wall -Werror | FileCheck %s
+
+#include <x86intrin.h>
+
+void test_mm_clwb(const void *__m) {
+  //CHECK-LABEL: @test_mm_clwb
+  //CHECK: @llvm.x86.clwb
+  _mm_clwb(__m);
+}